as alternative of the Asrock /2oJm6ua]http://[Suspicious link removed]/2oJm6ua bro btc 1 or /2oqj4aU]http://[Suspicious link removed]/2oqj4aUpro btc 2
found some of lower price 6 gpu and 7 gpu motherboards

7 gpu motherboards :

• MSI Z170A Gaming M5 /2pz7egn]http://[Suspicious link removed]/2pz7egn  130$
• MSI Z170A Gaming Pro Carbon /2pzhcP0]http://[Suspicious link removed]/2pzhcP0  140 $
• Gigabyte  GA-Z170X-GAMING 5 /2peJNvN]http://[Suspicious link removed]/2peJNvN  140$
• ASRock Z170 OC FORMULA /2oSXqzX]http://[Suspicious link removed]/2oSXqzX  233$

6 gpu motherboards

• MSI Pro Z170A SLI /2oqlYMQ]http://[Suspicious link removed]/2oqlYMQ 110$
• ASUS H170 PRO GAMING /2oSXNdN]http://[Suspicious link removed]/2oSXNdN  110.5 $
• MSI Z170A SLI Plus /2oT3rg9]http://[Suspicious link removed]/2oT3rg9  115$
• ASRock FATAL1TY Z170 PROFESSIONAL /2pzl3vs]http://[Suspicious link removed]/2pzl3vs 135$
• ASRock  Z170 EXTREME4 /2oJsTUB]http://[Suspicious link removed]/2oJsTUB  138.5$
• GIGABYTE GA-Z170X-Gaming 3 /2o1lIbV]http://[Suspicious link removed]/2o1lIbV  165$

sure there is more motherboards but need more search time
if you have any of those please give a feedback